Merge pull request #842 from PowerShell/andschwa/build-dwim

Import-Module PowerShellGitHubDev in build.sh

build.sh

@@ -2,7 +2,7 @@
 
 if hash powershell 2>/dev/null; then
     echo 'Continuing with `powershell -c Start-PSBuild`'
-    powershell -c Start-PSBuild
+    powershell -c "Import-Module ./PowerShellGitHubDev.psm1; Start-PSBuild"
 else
     echo 'No `powershell`, see docs/building/linux.md or osx.md to build PowerShell!'
 fi